Would a pullback in stocks be a surprise? WSJ's Spencer Jakab visits Mean Street with a look at the Citigroup U.S. Economic Surprise Index and why it has economists concerned. Photo: AP.

This transcript has been automatically generated and may not be 100% accurate.

I ... the ... CME Economic Surprise Index and how that may be telling us that maybe things aren't so hunky dory markets go up to try ... to get there and that's it it's like that as ... enthusiastically in college and leaders of the people is you can tell we can chart their inheritance in the know it's it's a really interesting index of clay why because ... it's not measuring any kind of economic indicators saw the measure and the weather in the measure in the colonists not saying whether its good or bad was measuring is ... how will their consistently wrong with this chart and it goes up and down like a yoyo a run of how how much economists move in herds and are wrong in her it's ... the boxes that ... it I mean it's that I think we know the students wanted to know that for a long time right I mean that economists to so to ... what we ... what he points out ... is that it's been a lot of this turning points he is when economists have gotten overboard and so that you ... keep on extrapolating ... the bad news for the good news with them throughout the day role in a real ear on ... it it tends to mark a turning point that the drug efficacy and not always but often that's right so last summer ... it was they were a lot recession you know I'd recession ... thirty percent forty percent loss to sixty percent chance of recession ... you had the gall euro ECRI but there are some of the last time he came out the calf Aleris AG still saying that the recession is right and when everybody says this recession odds are ... probably not recession ... I mean whenever one comes out and says you know in the sky is falling and for the hills ... then by that point the market do more with a market where is the market in August where the markets of September thirty it was when ... the CR agreed that call ... when the market bottom and then head off twenty six percent ... starting the next session October third time he he he I were on the top of the high low and the cousins had a ... rough few months but was over to the contrary indicator a kid and this is an interesting insight has always been for for contrary indicator because this this and that's been around for ... a bigger since two thousand and three but it basically that ... the average is zero of the index and it goes up as high as it's been almost a hundred it's been as low as minus one eighteen ... just measures how long will it doesn't zigzag around a hundred it goes up ... or down to the extremes know every every several months ... so does this prove that ... economists are mostly wrong or that their most wrong when he came to monitor ... they run impacts does prove that ... it proves that they like all us like humans because we have is a hunter gatherer brings read a mean so that you know ... by nine percent of our existence was in a chasing master loans and one percent has been ... looking at stock charts and sold well documented right mean ... we tend to extrapolate ... the recent past whether it's good or bad ... and were little slow to change on the agenda ... although I'm not ... a lot of that it would cut the connoisseur to the Wall Street economists ... these because ... they're basically painting ... you know they get a bonus when they're not that far out of consensus when you're at all when you're Fuller and the consensus a new look ... you'll either be a hero or a go ... more often than I'd give you think you'll be ago ... and so you stick he can sustain the crowds at a fair assessment ... I mean I think you know ... yet if you look it ... the last recession right ... how many Wall Street coming into my notebook of the sixteen or seventeen because Wall Street firms how many ... predicted the recession ... not just before halftime ... bought them on ... the week after the recession how many people that were particular sessions you ... in the same for the one before that zero so ... I mean they're not very good at calling the turning point ... no they're good at that ... you're describing things the good the extrapolate was happened recently but the top of it ... they were to get a good visiting with institutional investors ... and cheering conventional wisdom ... which is then carried back to them from the seashore ... uses conventional wisdom ... so they all kind of ... now picture DNDN they'll get paid ... the I couldn't put myself into cynical Spencer I think that they have some yet that that you can't ... say that they're all cut from the same call but you ... you not to all four of the more it would send naked ahead of the day are we are we ... do you think ECRI can be proven right are we heading back into recession ... you know what I think that dogs that we may be headed for a more of a slowdown that ... that some people expect recessions of ... the middle of the recession since the second World War that still have that all